Celebrations and Customs

Q: We are living in USA. Here every year people are celebrating Thanksgiving day. Our Muslims are also celebrating in the same way. Is it permissible for a Muslim to celebrate this day?

Q: Are hot cross buns, Easter eggs, egg marshmallows, etc halaal?

Q: There is a fatwa from Al Azhar that says it is allowed for Muslims to congratulate non-Muslims on their religious days such as Christmas and this action
comes in the virtue of treating others (non - Muslims) well. Allah Ta'ala says in the Holy Quraan, "say to people good words" and "certainly Allah recommends the justice and being good to others." 

Q: Is it permissible to give presents to non-Muslim co-workers a few days before or after Christmas with the intention that one is giving the present as an Islamic display of good character?

Q: Is birthday parties haraam? If a person sends to me a piece of her birthday cake, will it be haraam for me to eat? To send ones children to
birthday parties will it be also haraam? Please explain this issue well and if it is haraam why?

Q:

1. Is it permissible to send seasonal greeting cards to non-Muslims at the time of Christmas so long as there are no religious symbols on them and without the intention of celebrating or supporting Christmas?
2. Can the following from al-ashbaah be used as a justification for sending seasonal greeting cards at Christmas time?

In al-ashbaah it states that if a person says regarding a non Muslim: "May Allah let his kingdom last for a long time" and his intention is that he may be given hidayat in future, or that the Muslims could benefit through his contributions of jizyah etc, then this is permitted. 

Q:

1. Is it permissible to say have a happy new year when Islamic new year starts (month of  Muharram starts)?
2. Is it permissible to say have a happy new year when the Gregorian calendar new year starts (month of January starts)?
3. If its not permissible to say have a happy new year then what is the reason?
4. What did Prophet Peace be upon him and the Sahabah do or say to each other when the new year commenced?

Q: I had a question what's the ruling on Muslims celebrating non Muslims holiday?

Q: Is it permissible to write the following line in a letter which will be sent to employees of a company before holidays: ".. and may we also convey our best wishes to John & Henry and other colleagues who are celebrating Christmas"? I.e. without wishing them Merry Christmas but just "convey our best wishes"

Q:  What is the ruling on uttering "Happy holidays" to disbelievers (i.e. Christians)?